The present invention generally relates to electric connectors, and more particularly, to connectors having enhanced grounding characteristics, which are appropriate for use in high-frequency circuits.
Electric connectors are often used in connecting printed circuit boards together. In the construction of such connectors, it is known to use a metal shield to surround the insulative housing in order to preventing the leakage of high-frequency signals from the joint(s) at which the printed circuits boards or associated electric parts are connected together. Examples of high-frequency connectors using metal shields are disclosed in Japanese Patent Application Laid-Open Nos. 4-255678 and 5-217630. These high-frequency connectors use an insulative housing with a plurality of terminals fixed in the interior of the housing and a metal shield fixed to the exterior of the housing, and are designed so as to ground any high-frequency signals appearing on any terminals by way of the metal shield. The inner terminals, the exterior shield and the intervening insulative housing combine to act as a capacitor and capacitive coupling occurs which passes the high-frequency signals of the terminals to the grounding shield.
However, in such constructions, there is an appropriate fear of permitting local high-frequency paths which occur between the terminals and the metal shield to function as antennas, thus causing radiation of high-frequency signals to neighboring terminals. In an attempt to avoid this type of interference between terminals disposed along the opposing longitudinal sides of the connector which carry high-frequency signals, the exterior metal shield is grounded at the opposing ends of the connector. However, as the length of the connector increases and the number of terminals which extend along the longitudinal extent of the connector also increases, the likelihood of an antenna effect occurring between the metal shield and terminals likewise increases. The increased size of the connector and increased number of terminals increases the likelihood of inducing undesired signals because the grounded ends of the connector move farther away from the high-frequency terminals and because the high-frequency signals seek a low impedance path to ground, they tend to propagate through a nearby terminal and through the circuitry of the printed circuit board rather than the groundpaths at the ends of the connector.
The present invention is directed to an improved connector which avoids the aforementioned shortcomings and reduces the likelihood of an antenna effect from occurring that will lead to radiation of high-frequency signals by increasing the number of groundpaths along the length of the connector.